.sidebar {
  padding: 1.5rem 1.5rem 1.5rem 0; // no left padding on big screen
}

.sidebar-item {
  &:not(:last-child) {
    margin-bottom: 1rem; // space between sidebar items
  }

  h3 {
    margin-bottom: 0.25rem; // space between head3 & lists
  }

  ul {
    list-style-type: none;
    margin: 0 0.1rem; // little space
  }

  & > div,
  & > nav {
    margin: 0 0.1rem; // little space
  }

  & > img {
    margin: 0.5rem 0.25rem 0 0.25rem;
    width: 100%;
    border-radius: 2px;
  }
}

@media screen and (max-width: $width-md) {
  .sidebar {
    padding: 1.5rem;
    display: flex;
    flex-direction: row;
    flex-wrap: wrap;
    justify-content: space-around;
  }

  .sidebar-item {
    width: 40%; // max 2 modules per line

    // space only at first 2 modules
    .sidebar-pages,
    .sidebar-tags {
      margin-bottom: 1rem;
    }

    .sidebar-links,
    .sidebar-bgm {
      margin-bottom: 0;
    }

    & > img {
      margin: 0.5rem 0.25rem 0 0.25rem;
      width: 75%;
      border-radius: 0.25rem;
    }
  }
}

// single page part
.sidebar-toc {
  ul ul {
    font-size: 0.875rem;
    padding-left: 0.5rem;
    margin-bottom: 0.25rem;
  }

  position: sticky;
  top: 1rem;
}
